The creator and cast of “Downton Abbey” admit they suspected when the series debuted that they might become relatively famous faces in the United Kingdom, where the hit series originates. But they never suspected the juggernaut period drama would propel them to become celebrity sensations around the globe.

As the series enters its fourth season, creator Julian Fellowes has seen it become a pop culture phenomenon. “One of the odd things about this particular show is that it's been very successful in all sorts of bases like China or Africa, and you think ‘I wonder what they're getting from it’ sometimes,” he muses.

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As the show and its stars have garnered various Hollywood acting awards nominations and traveled to the United States to promote the series, which is broadcast on PBS’s “Masterpiece” several months after its original presentation on British television, they’ve gotten a clear indication of the passion “Downton” inspires in its American audience.

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“It feels that Americans fans have more of a confidence, I guess, to come over and say something to us and say that they love the show,” says star Michelle Dockery, who stars as the tragedy-prone Lady Mary Crawley. “The British are more reserved, so they'll maybe look but they won't say anything."

“I think perhaps America people really do think I'm a Lord or an Earl or whatever,” chuckles Hugh Bonneville, who plays Robert Crawley, the Earl of Grantham. “Back in the UK, people see me in the supermarket and aren't quite as surprised because they know it's not real."

“People have taken it very much to their hearts here, and in a slightly surreal way sometimes,” adds Bonneville. “We were invited to a wedding in Florida by complete strangers because they wanted Lord Grantham at their table. I did have to write back and point out that he was only a fictional character."

After moving about largely unrecognized in London, Sophia McShera, who plays the assistant cook Daisy, got her first taste of fame in America during a visit to New York City. “People were really recognizing me – it was bizarre!” she laughs. “I went to the theater with Lesley [Nicol] who plays Mrs. Patmore, and we nearly got mobbed in the theater."

“I don't think anyone gets a job and goes ‘We're probably going to be a worldwide hit,’” admits McShera, who’s found herself stunned by encounters with celebrity fans of the series. “I met Steve Buscemi, and he and his wife loved the show. I was chatting to him for ages, and I was like 'No, wait – this is not right. You can't watch it.' It's very exciting. Someone just told me that Tom Hanks watches it. My mum absolutely loves him, so she'll be happy to hear it.”

The stars themselves confess to being fans themselves when it comes to the show’s addictive characters and plotlines outside their own, digging into each new script for the latest twists facing their favorites. “I love reading Anna and Bates,” enthuses Dockery. “I think if I wasn't in the show I would follow their story more than anyone's really. I just love their relationship. I love Anna as a character. She's like the heart of the show. She's a constant. She's the eternal kind of generous and good person."